Factors Affecting Chlorine Behavior in Pressed Marine Sediment Samples under X-Ray Fluorescence Analysis

It was found that salt efflorescence gradually develops on the surfaces of pellets pressed from marine sediments after analysis by X-ray fluorescence spectrometry when the pellets remain exposed to laboratory air during the summer–autumn period. Chemical characterization identifies the efflorescence as sodium chloride. In some cases, the intensity of the chlorine Kα line increases by a factor of up to 10 relative to its initial value, and the sodium Kα line exhibits a comparable increase. In contrast, the intensities of the X-ray fluorescence lines from the other major elements in the sample in some cases decrease more than twofold. Grinding the pellets followed by back pressing restored the analytical results to their initial values. We evaluates factors that promote sodium chloride migration to the pellet surface, including fluctuations in air humidity and temperature in the storage room, as well as the residual moisture content of the sample or of the binder during the pellet preparation. This behavior arises from the high NaCl content of marine sediments, although similar processes may also occur at lower sodium chloride concentrations.